Study Reveals Defects Reduce Brightness in Carbon Nanotubes

Published on February 2, 2012 at 1:12 AM

By Cameron Chai

A Rice University study on fluorescence of single-walled carbon nanotubes has discovered that the brightest nanotubes of identical length demonstrate uniform fluorescence intensity and their brightness varies proportionally with their length.

However, the study has also revealed that brightness of nanotubes of identical length is not the same due to chemical reactions or defective or damaged structures that made atoms to attach onto the surface.

The study by Bruce Weisman, a chemist at the Rice University lab, has been reported in an article titled ‘How Nanotubes Get Their Glow’ in ACS Nano, a journal of the American Chemical Society. Weisman studied the impact of defects and lengths of single nanotubes on their fluorescence. Here, the nanomaterials emit light at near-infrared wavelengths.

Late last year, Weisman together with Tonya Leeuw Cherukuri and Dmitri Tsyboulski first reported the study. In the report, they described a method through which Cherukuri studied the features of 400 single nanotubes of a particular physical structure, (10,2). They selectively viewed the particular type of nanotube by applying spectral filtering.

Weisman explained that his team singled out one or two secluded nanotubes simultaneously in a diluted sample and then measured their lengths by studying videos of the moving nanotubes captured using a specially designed fluorescence microscope. The videos also helped Cherukuri to record the optimum brightness of the nanotubes.

Weisman commented that most of the nanotubes are fluorescence underachievers that do not fluoresce to their full capacity. The team sought to understand the impact of growth methods and processing of nanotubes on their fluorescence so as to study the impact of defects on brightness. Jason Streit, a graduate student, has found a way to automate Cherukuri's method that allows the researchers to image and analyze several nanotubes immediately, Weisman concluded.